1. Field of the Invention
The present invention relates to an angle detecting device, more particularly to an angle detecting device for detecting crank positions or angles in an internal combustion engine by utilizing the Hall effect.
2. Description of the Related Art
FIGS. 7, 8 illustrate a conventional angle detecting device as described in the applicant's previous application (Japanese Pat. Laid Open No.2-240585). FIG. 7 is an exploded view, and FIG. 8 is a vertical sectional view. A resin-made frame 1 comprises a housing portion 11, a connector 12, a magnetic-flux guide supporter 13 and mounting means 14. The housing portion 11 includes an inner wall 11c, a bottom portion 11a, an opening 11b and a lower surface 15. A hybrid integrated circuit part 2 mounts a Hall element 2 a for converting changes of the magnetic flux into electric signals and also other circuit elements. Leads 21 are for output of the signals generated by the hybrid IC part 2. A plate 3 formed by stamping a non-magnetic stainless-material plate comprises positioning means 31 for defining the position of the IC part 2, engaging means 32 for a second magnetic-flux guide 42, and a positioning bendable portion 33 for abutting the bottom portion 11a when the plate 3 is inserted into the housing portion 11. The bendable portion 33 defines the position of the plate 3 in the housing portion 11 by naturally bending along the portion indicated by 33a when the plate 3 is inserted, and by the abutting surface 33b abutting the bottom portion 11a when the plate is inserted up to the right position. The engaging means 32 is a through hole.
A first magnetic-flux guide 41 has a recess 41a for engaging with a magnet 5 and has a pair of engaging projections 41b for connecting to the magnetic-flux guide supporter 13 provided on the frame 1. Filler 8 shown in FIG. 8.,e.g., silicon gel, is for protection of the circuit elements and also for electrical insulation. A cover 6 is for closing the opening 11b. Inserted conductors 7 have their inside ends 71 extended into the housing portion 11 and their outside ends 72 extended out of the frame 1 into the inside space of the connector portion 12. The inside ends 71 form connecting ends to the leads 21 of the IC part 2, and the outside ends 72 form connector pins in the connector portion 12. The inserted conductors 7 penetrate a pre-molded portion 18 between the frame 1 and the connector portion 12. In a magnetism gap G, a magnetic flux shutter 100 rotates synchronously with a detected subject.
To assemble the angle detecting device designed as above, adhesive is applied to the portions A shown in FIG. 7, and then the plate 3, the IC part 2 and the second magnetic-flux guide 42 are integrally assembled as shown in FIG. 7 into a pre-assembly unit (not shown). Adhesive is also applied to the bottom portion 11a including the bottom surface and a part of the inner wall 11c in the housing portion 11, and then the unit is inserted into the housing portion 11 in the indicated direction by an arrow B. The unit is pushed in, with the bendable portion 33 bent along the portion 33a, until the abutting surface 33b abuts the bottom surface, as shown in FIG. 8. Next, the leads 21 of the IC part 2 and the connecting ends 71 of the inserted conductors 7 are connected at an area J by spot welding.
The magnet 5 is fixed with adhesive into the recess 41a of the first magnetic-flux guide 41, and then the guide 41 with the fixed magnet 5 is fitted and fixed, such as with adhesive, to the magnetic-flux guide supporter 13. Next, after the filler 8 is filled in the housing portion 11 in which the pre-assembly unit has been contained, the cover 6 is mounted and fixed with adhesive onto the frame 1, sealing the opening 11b.
To detect the crank positions or angles of an internal combustion engine with the device designed as above, the magnetic-flux shutter 100 synchronized with the internal combustion engine is rotated in the magnetism gap G. The magnetic-flux shutter alternates allowing and shielding the magnetic flux towards the Hall element 2a. The Hall element 2a switches on and off its output signals according to the change in the magnetic flux, supplying electric signals indicative of the rotation angle in the cycle of the internal combustion engine.
In assembly of a conventional angle detecting device, an adhesive is used between the plate of the pre-assembly unit and the bottom portion of the housing in order that the unit including the plate, the IC part ad the second magnetic-flux guide is fixed in the housing portion of the frame. The curing of the applied adhesive requires substantial work and time, e.g., keeping it in the atmosphere of 150.degree. C. for several hours, and the above work must be processed by batch processing, therefore raising the cost. Thus, the conventional design is inappropriate for mass production.